Caution: Even though this method has proven to give higher efficiency, there are some problems associated with it, especially in a hot country like India. Please consider this article only as an alternative thought/possibility and try to address the limitations, before you implementing what is mentioned below.
Solar panels are not only expensive, they produce maximum power only for a few hours everyday, during peak sunshine (that too way below its rated capacity). In winters and rainy days, the solar power output will be lesser. Consumers usually install higher capacity solar panels, to achieve expected power output during all seasons. At least with the current solar module costs, this can shoot up the expenditure considerably.
Consumers from around the world face this issue, especially those from Europe and Northers parts of America, as the amount of sunlight they get is much lesser. Some of them have thought out-of-the-box and decided to use reflectors (like mirrors, etc.) to increase the amount of sunlight that falls on the solar panels. This simple technique increases the electric power output considerably. Don't believe me? Look at this small experiment. While you are there, try to read the comments in that article, as well.
People have used all types of reflective materials (glass, reflective paint coated surface, slab painted white, tin-foil/aluminum-foil coated surface, etc.), either on the ground or somewhere else around the solar panels in order to reflect the maximum amount of sunlight onto it. One innovative technique I found was 'V-type' arrangement with solar panels on one side and reflectors on the other side. Some people have even used reflective materials on the walls of the building, etc. in order to reflect more sunlight towards the solar panels. Ford is planning to use a spherical crystal (Fresnel lens) to concentrate light on the solar panels mounted on the roof of its electric car, to increase the power output.
Since making such reflectors would cost only a fraction of the price of buying new solar panels, I am sure this technique will interest a lot of people around the world, especially in developing countries like India.
However, the biggest issue with this approach is: Reflecting sunlight this way heats up the solar panel and may result in damaging the solar modules or reducing its life! Solar panels (especially crystalline-based ones) operate at their best efficiency over a limited range of temperatures; it has been noted that any increase in temperature will decrease their efficiency/power output. This also brings up the question of whether using crystalline solar panels in hot countries near the equator is even recommended. Manufacturers generally try to address the climatic issue before distributing their products (or) the installer/solution provider will inculcate some (additional) cooling methodologies to offset the generated heat due to high temperatures.
Hence, using reflective surfaces to focus more light on solar modules will heat up solar panels, and - along with the already excessive heat generated in countries like India - may void the manufacturer warranty, cause damage or reduce the life-time of solar modules.
To work around this problem, people have resorted to using reflectors only during early mornings/late evenings, only during winters and not during summers, etc. so that the temperature increase will have little effect. However, there is no consensus on how much temperature inside the modules is too much!
People also use cooling techniques like washing the solar modules frequently, using water sprinklers, using heat-sinks, using liquid-tube cooling and others to reduce the temperature on the solar panels. Think about this: heat is actually required (for hot water, etc.), so why not extract it from poorly performing (hot) solar modules and use it to heat water? Makes a lot of sense.
Only, someone needs to integrate all these components - solar panels, reflectors, cooling techniques, etc. and actually do a field test, to come to a concrete conclusion. I don't find such a comprehensive testing being reported online. To System Integrators: Why not take up this challenge? It will surely help you differentiate your services and reduce cost, which will win more customers/projects. Or college students can try setting up a pilot project and test it over a period of time, for their final year project/masters thesis, and report its findings.
Without documenting the long-term effects of using reflectors along with solar panels and determining the best cooling technique, it maybe too risky for consumers to try it out.
